This is an application for an Independent Scientist Award (K02). During the award period the applicant plans to continue his research into the etiology and neurobiologic mechanisms in autism and to obtain additional training in cognitive neuroscience. The overall aim of this work is to elucidate the pathogenesis of autism through development of an integrated program of research involving family, molecular genetic and neuroimaging studies of autism and the broader autism phenotype. The aim of the family study is to explore the boundaries of the autism phenotype by examining a range of behavioral, cognitive, and biological characteristics in autistic probands and their relatives. The aim of the molecular genetic study is to conduct a genome search, using several different analytic strategies, to find genetic loci that contribute to the autism phenotype. Neuroimaging studies being conducted and proposed are aimed at examining anomalous patterns of growth and organization of the brain in individuals with autism and the broader autism phenotype through the study of abnormalities in brain size, shape and function. Career development activities in this application link directly to the research proposed and include training in: (1) the instrumentation and application of MRI, PET and fMRI; (2) training in behavioral neurology and neuropsychology; and (3) training in neuroanatomy and developmental neurobiology, as these areas related to the study of autism.